Many individuals have a skin complexion which does not tan readily on exposure to sunlight. Others achieve a tan only with great discomfort and possibly adverse effects to the skin due to exposure to sun's rays, e.g., sunburn. Yet, attainment of a tan is highly desired by many individuals for cosmetic and other reasons, especially if this can be accomplished effectively without the usual exposure to the sun, i.e., through skin-tanning agents.
In other instances, individuals who tan with difficulty may desire to enhance or extend the life of a naturally acquired tan without re-exposure to the sun. Also, a suntan may be desired when weather conditions do not permit the sun exposure necessary to acquire a tan.
Acquisition of a natural tan by exposure to the sun may be almost impossible for those very light skin persons who tend to burn rather than tan. In addition, the deleterious effects of excessive exposure to sunlight are becoming more generally recognized.
It is known in the art that an artificial tan can be achieved by applying skin-tanning agents to the human skin in a suitable vehicle or base. Examples of known skin-tanning agents include hydroxyaldehydes, such as dihydroxyacetone, see U.S. Pat. Nos. 2,949,403 and 5,232,688. Also known as skin-tanning agents are imidazole and various imidazole derivatives, such as 4-(hydroxymethylimidazole); see U.S. Pat. No. 5,252,322, Stoner et al, issued Oct. 12, 1993.
U.S. Pat. No. 2,949,403, Andreadis et al, issued Aug. 16, 1960, discloses compositions of and methods of using dihydroxyacetone as a tanning agent for the human epidermis. It has been reported that dihydroxyacetone reacts with skin proteins and amino acids to elicit its skin coloring effect. Since the 1960s, several compositions using dihydroxyacetone as an active ingredient have been reported. These compositions include a topical composition containing dihydroxyacetone and various dyes, such as catch powder, dogwood powder and walnut powder (the dyes are employed to offset the undesirable orange cast or hue which results from the use of dihydroxyacetone on fair skinned humans, see U.S. Pat. No. 4,708,865, Turner, issued Nov. 24, 1987). These also include compositions containing dihydroxyacetone and sunscreen compounds, such as octyl dimethyl PABA (see, for example, U.S. Pat. No. 4,434,154, McShane, issued Feb. 28, 1984, and U.S. Pat. No. 3,177,120, Black et al, issued Apr. 6, 1965). Further, dihydroxyacetone has been formulated into oil-in-water emulsions, into preparations containing up to 50% alcohol which tend to dry the skin, and into “creamy bases”, such as are found in hand and face lotions and creams.
U.S. Pat. No. 5,232,688, Ziegler et al, issued Aug. 3, 1993, discloses compositions for self-tanning of skin which include an alpha-hydroxy substituted ketone or aldehyde, such as dihydroxyacetone or erythrulose, a polyacrylamide, and a pharmaceutically-acceptable carrier.
U.S. Pat. No. 5,514,367, Lentini et al (assigned to Estee Lauder), issued May 7, 1996, describes self-tanning compositions which include a self-tanning agent (such as dihydroxyacetone) together with cyclodextrin. These compositions are said to improve storage stability and prevent the formation of Maillard reaction odors during use of the composition.
U.S. Pat. No. 6,268,353, Chaen et al, issued Jul. 31, 2001, describes the use of trehalose and/or maltitol to prevent the formation of odiferous aldehydes and fatty acid decomposition products in food products, as well as in body lotions. This patent does not describe the use of self-tanning products or the Maillard reaction odors resulting from the topical use of such compositions.
U.S. Published Patent Application 2006/0148757, Oku, published Jul. 6, 2006, uses α-oligoglucosyl-α,α-trehalose to prevent the formation of volatile aldehyde and fatty acid decomposition products which can form odors in food and skin lotion products. This application is related to U.S. Pat. No. 6,268,353, discussed above.
U.S. Published Patent Application 2008/0003245, Kroepke et al, published Jan. 30, 2008, describes cosmetic compositions which include 1,3-dihydroxyacetone (DHA) together with octyl salicylate. The purpose of these compositions is to stabilize the DHA in the composition.
U.S. Published Patent Application 2008/0058738, Roberts et al, published Mar. 6, 2008, describes the use of expanded starch particles combined with transition metals to absorb and bind odor molecules in absorbent articles.
PCT Published Patent Application WO 2007/060021, Brillouet et al, published May 31, 2007, describes compositions which are used to stabilize dihydroxyacetone in product in order to prevent the formation of odiferous decomposition products. These self-tanning compositions include a self-tanning agent, such as dihydroxyacetone, a modified starch gelling agent, and optionally a branched polysaccharide gelling agent.
While dihydroxyacetone has been widely employed as a skin-tanning agent, commercial preparations containing dihydroxyacetone suffer from a number of drawbacks. One such disadvantage is the physical and chemical degradation of dihydroxyacetone-containing preparations over extended periods of time, for example, during warehouse storage or after consumer purchase. Such degradation leads to discoloration, the development of unpleasant odors, and an overall loss of stability and skin-tanning efficiency. Several of the references discussed above attempt to address this concern. A further disadvantage of such preparations is the development of aesthetically-unacceptable odors following application of such preparations to the skin. This is thought to occur as the result of the Maillard reaction, a reaction between dihydroxyacetone and the skin which results in skin-tanning. It is this latter concern which the present invention addresses.